阅读说明：本技术 一种改进pvt法生长碳化硅单晶的热场结构 (Thermal field structure for growing silicon carbide single crystal by improved pvt method ) 是由 不公告发明人 于 2021-09-15 设计创作，主要内容包括：本发明涉及一种生长大尺寸碳化硅单晶的热场结构,具体涉及一种PVT法生长大尺寸化硅单晶的改进热场结构。该结构整体由侧面保温结构、底部保温结构、籽晶固定结构、感应线圈两个、si原料用的坩埚、c原料用的坩埚、升华气体输送管道构成,其特征在于：侧面保温结构呈圆环形,是由多层纤维砖结构搭接而成,底部保温结构边缘与侧面保温结构相连接,该结构呈圆台形,籽晶固定结构位于热场顶部,si坩埚位于保温材料内部左侧,c坩埚位于保温材料内部右侧,两个感应线圈分别环绕与两个坩埚的外壁,升华气体管道分别连接两坩埚顶部的中心位置,气体出口位于籽晶固定装置底部,该热场结构,设计合理,温度分布均匀,实现了sic单晶生长过程的si和c气体饱和浓度的合理比例输送,降低晶体内部缺陷。(The invention relates to a thermal field structure for growing large-size silicon carbide single crystals, in particular to an improved thermal field structure for growing large-size silicon carbide single crystals by a PVT (physical vapor transport) method. This structure is whole by side insulation construction, bottom insulation construction, seed crystal fixed knot construct, induction coil two, crucible that si raw materials were used, crucible, sublimation gas pipeline that c raw materials was used constitute its characterized in that: side insulation construction is ring shape, it is formed by the overlap joint of multilayer fibrous brick structure, bottom insulation construction edge is connected with side insulation construction, this structure is the round platform shape, seed crystal fixed knot constructs to be located the thermal field top, the si crucible is located the inside left side of insulation material, the c crucible is located the inside right side of insulation material, two induction coil encircle respectively with the outer wall of two crucibles, the central point that two crucible tops were connected respectively to the sublimation gas pipeline puts, gas outlet is located seed crystal fixing device bottom, this thermal field structure, and reasonable in design, the temperature distribution is even, the reasonable proportion of si and the gaseous saturated concentration of c that has realized the single crystal growth process of sic is carried, reduce crystal internal defect.)

1. An improved thermal field structure for growing large-size silicon single crystals by a PVT method. This structure is whole by side insulation construction, bottom insulation construction, seed crystal fixed knot construct, induction coil two, crucible that si raw materials were used, crucible, sublimation gas pipeline that c raw materials was used constitute its characterized in that: the side heat-insulating structure is in a circular ring shape and is formed by overlapping a plurality of layers of graphite fiber brick structures, the edge of the bottom heat-insulating structure is connected with the side heat-insulating structure, the structure is in a circular truncated cone shape, the seed crystal fixing structure is positioned at the top of the thermal field, the si crucible is positioned on the left side inside the heat-insulating material, and the c crucible is positioned on the right side inside the heat-insulating material; two induction coils encircle respectively with the outer wall of two crucibles, the central point that two crucibles tops were connected respectively to the sublimation gas pipeline puts, and gas outlet is located the junction of two crucible sublimation pipelines.

2. The improved thermal field structure for growing large-size silicon single crystals by the PVT method according to claim 1, wherein the side heat-insulating structure is a circular ring and is formed by overlapping a plurality of layers of graphite fiber brick structures, and the inner diameter of the improved thermal field structure is phi 200-phi 240mm, and the outer diameter of the improved thermal field structure is phi 280-phi 300 mm.

3. The improved thermal field structure for growing large-size silicon single crystals by the PVT method according to claim 1, wherein the bottom thermal insulation structure is positioned on the bottom layer of the thermal field, the side wall of the bottom thermal insulation structure is tangent to the side thermal insulation structure, the structure is in a shape of a truncated cone, the diameter of the structure is phi 180-phi 210mm, and the thickness of the structure is 30-60 mm.

4. The improved thermal field structure for growing large-size silicon single crystal by PVT method as claimed in claim 1, wherein the truncated cone-shaped seed crystal fixing structure is located on the top layer of the thermal field, and has a diameter of Φ 100 and 130mm and a thickness of 20-60 mm.

5. An improved thermal field structure for growing large-size silicon single crystal by PVT method as defined in claim 1, wherein the induction coil surrounds the outer walls of the two crucibles, the diameter of the wire is 10-40mm, the height is 200-300mm, and the moving stroke is 50-70 mm.

6. An improved thermal field structure for growing large-size silicon single crystals by PVT method as claimed in claim 1, wherein two crucibles for holding si raw material and c raw material are located at left and right sides of the bottom of the thermal field, the top of each crucible is provided with a conveying pipeline for sublimed gas, and the two pipelines are joined at the bottom of the seed crystal.

Technical Field

The invention relates to a thermal field structure for growing large-size silicon carbide single crystals, in particular to an improved thermal field structure for growing large-size silicon carbide single crystals by a PVT (physical vapor transport) method

Background

The silicon carbide as a third-generation semiconductor material has the advantages of being several times higher than that of the traditional silicon material in forbidden bands, high in breakdown electric field intensity, good in thermal stability and the like, and has important significance in electronic application fields such as high temperature, high voltage, high power, photoelectricity and microwave and extreme environment application fields such as aerospace, military industry and nuclear energy.

The Sic single crystal growth mode mainly includes two types of HTCVD and PVT, however, the PVT process method has many advantages such as high yield and low cost, and thus becomes the first choice technology of the current commercial production, and the Sic production technology shows wide market prospect with the increase of market demand, however, in order to enter the industrialization stage, various manufacturers need to overcome a series of problems such as saturation concentration and proportion uniformity of si and c gases in the Sic single crystal growth process, wherein the problem of imbalance of sublimation gas proportion caused by the difference between si and c melting points becomes the first research subject.

Disclosure of Invention

An improved thermal field structure for growing large-size silicon single crystals by a PVT method. The whole structure consists of a side heat insulation structure, a bottom heat insulation structure, a seed crystal fixing structure, two induction coils, a crucible for si raw materials, a crucible for c raw materials and a sublimation gas conveying pipeline.

The invention also has the following features:

1. the improved thermal field structure for growing the large-size silicon single crystal by the PVT method is characterized in that the side heat-insulating structure is annular and is made of hard graphite;

2. the improved thermal field structure for growing the large-size silicon single crystal by the PVT method is characterized in that the bottom heat-insulating structure is in a round table shape and is a packaged graphite carbon felt;

3. the improved thermal field structure for growing the large-size silicon single crystal by the PVT method is characterized in that the structure is a truncated cone-shaped seed crystal fixing structure, and a copper induction coil surrounds the outer walls of two crucibles;

4. the improved thermal field structure for growing the large-size silicon single crystal by the PVT method is characterized in that a conveying pipeline of sublimed gas is arranged at the top of each crucible, the two pipelines are intersected at the bottom of the seed crystal, and the pipeline is made of graphite.

Has the advantages that:

1. the reasonable design of the split crucible structure effectively solves the problem of imbalance of the proportion of the sublimation gas caused by the difference of the melting points of si and c, ensures the reasonable proportion of si and c in the growth process of silicon carbide, and improves the crystal quality.

2. The device can realize controlling the heating temperature of two crucibles respectively, and then realize rationally allocating sublimation gas's delivery volume and saturated concentration, overcome the growth process of sic single crystal, the problem of two proportion hard to control reduces crystal internal defect.

3. The device is succinct in operation, and degree of automation is high, reduces personnel's labour, effectively reduces production manufacturing cost.

Brief description of the drawings and detailed description

The invention is described in detail below with reference to the accompanying drawings:

FIG. 1 is a schematic diagram of an improved thermal field structure for growing large-size silicon single crystals by a PVT method, a circular ring-shaped side thermal insulation structure 2 is arranged on the outer layer of a thermal field, a layer of bottom thermal insulation structure 5 is arranged at the bottom of the inner layer of the thermal field, a crucible structure 8 for containing Si raw materials is arranged on the left side inside the thermal field, the edge of a crucible surrounds a coil structure 7, a crucible structure 3 for containing C raw materials is arranged on the right side, the outer layer also surrounds the coil structure 4, two crucible connecting pipelines 9 are arranged on the top of the crucible and intersect at the bottom of the seed crystal, a seed crystal fixing structure 1 is arranged at the center of the top of the thermal field, and a seed crystal 6 is arranged at the bottom of the device.